I had been aware of Kurzweil during the K250 and K1000 eras, but what really turned my head was the K2000. Suddenly, what had been a line of sample playback devices evolved into a powerful synthesizer with the introduction of Variable Architecture Synthesis Technology (VAST). My first hands-on experience was enough to sell me, as I came home from that trip to my local dealer with a K2000 and a new perspective.

Kurzweil has iterated numerous times on that basic design, even through a disastrous period of uncertain ownership that saw them slip from the spotlight. The thing is, their offerings are still astonishing instruments with few rivals - and they just keep getting better, with the Kurzweil Forte as the most recent iteration.

No, this isn’t the semi-mythical K3000. There’s no wholesale reinvention to be found, but rather a whole lot of refinement.

Virtually everything that stood out about the K2000 is still here: the ability to add color and life to otherwise static samples or mangle them beyond recognition. Consistent use of real world units like hertz, cents, and decibels throughout the synthesis engine. The ability to load samples to complement the ROM content. Sixteen channel multi-timbrality with dynamic voice allocation, and a host of features that make the instrument a compelling master controller.

Bread and Butter Powerhouse

It’s no wonder that so many Broadway shows have relied on Kurzweil keys for their productions. It’s a great way to build a solid foundation of bread ‘n butter sounds that can be tweaked to sit just right in a mix.

All of the ROM samples from earlier VAST keyboards are present in the Forte, so there’s a healthy mix of orchestral content, percussion, bass, and keys but what’s most noteworthy are the updated classic keys in the latest ROM. New multi-gigabyte samples for Yamaha and Steinway pianos, Clavinet, Wurlitzer, Rhodes, and Celesta are outstanding additions. Add in half-damper support and string resonance, and it’s clear that Kurzweil was serious about appealing to the gigging musician playing a wide range of traditional keyboard parts.

Even if you don’t dig deep into sound design, the array of factory and third-party sounds that do so on your behalf is impressive. There’s a reason why I stuck with my K2500XS for more than two decades and was able to shrug off GAS for so many other digital synthesizers along the way.

Evolution of VAST

Of course samples are just raw material for the VAST engine. From inception, it has been a flexible pipeline of DSP blocks to help shape those samples into a playable instrument or transform it into more exotic, experimental sounds suitable for electronic and industrial soundscapes.

The quickest way I could think of to explain why I remain passionate about VAST twenty-eight years later is a quick rundown of things that changed somewhere along the way between the K2000 and the Forte. I’ve called out specific synthesis features that I‘m pretty sure are unique to the Forte here, but will cover the more substantial physical changes in another section:

Most significantly, the K2000 and K2500’s very basic original effects have been completely replaced. KDFX is a digital effects engine worthy of VAST. Hundreds of effects algorithms can be chained together in arbitrary order and modulated in real time. Effects chains can be global, with per-voice send levels, insert chains affecting specific MIDI channels, or even be tied to specific groups of layers within a program. The number of concurrent effects available on the Forte is double any previous VAST instrument and four times the original incarnation, allowing 32 KDFX “blocks.”

Polyphony has Increased from the original 24 voices to 128.

KB3 mode introduced physical modeling of Hammond organ tones with complete drawbar support, alongside KDFX Leslie simulations. The Forte takes this further by providing a dedicated KB3 engine, so every drawbar can sound without reducing the full 128 voice polyphony available for other MIDI channels.

New anti-aliased virtual analog oscillators that can morph between classic shapes in response to modulation, and updated filter algorithms modeling classic ladder filter designs. These were originally part of the legendary VA-1 prototype that have since been integrated as part of VAST.

Cascade mode allows any of the 32 layers within a program to take its input from any other layer, allowing incredibly complex DSP processing chains.

Master EQ and compression controls on the front panel allow existing sounds to be quickly tailored for a live setting or studio need.

Presets and user sounds can be categorized and searched by name to make sifting through large numbers of programs straightforward.

The initial restriction of one 32-layer “drum program” capable MIDI channel is gone. All MIDI channels are now equally capable with one exception: KB3 mode operates on one channel at a time.

Sophisticated arpeggiators are available on all MIDI channels concurrently, complete with a step sequencing mode.

Arbitrary sequences can be configured as “riffs” and assigned to trigger keys.

New to Forte: Modern Hardware

In addition to some minor tweaks to the sound engine noted above, there are more significant changes to the physical Forte hardware.

Most obviously, the Forte finally replaces the low-resolution monochrome display and user interface that dates back to the K2000 to a higher density color LCD. Every aspect of the user interface has been refined, in many cases combining information from two or more pages into a single display. I was quite surprised to realize that the display isn’t actually larger, it’s a comparable size with a taller aspect ratio, but it is much more effective.

The 16GB of sample ROM in the Forte is a huge step up from prior models, adding multi-gigabyte samples of classic keyboard instruments as noted above. It’s also only part of the story “Flash Play” story. There’s enough flash storage to allow 3.3GB of user samples to be loaded – and the full 19.3GB of samples are always available without load times, even after turning the instrument off and back on.

Many VAST instruments dating back to the K2500 have had a collection of sliders for real-time control including drawbar simulation. True to form, there are nine prominently placed assignable sliders and switches on the Forte but one of the long-standing issues has been addressed: when switching programs you can now see the current value associated with a slider by virtue of an LED ladder beside each physical control. This is a welcome addition, and pairs well with global settings to allow the value to jump immediately when a slider is moved, or to require the slider to move past the current value first.

These real-time controls are further improved by coming up with a common control scheme across all presets: by convention there’s a switch dedicated to turning reverb on or off and the corresponding slider adjusts its wet/dry mix. These are still completely assignable, but it’s nice to have predictable locations for values that do apply. There’s also a handy preview that shows up on screen any time an input modulates some destination, telling you immediately what is being adjusted.

Not Without Compromise

Obviously there’s a lot I adore about the Forte. It’s a significant step forward and easily among the most flexible hardware instruments available. I can’t think of anything I’d rather own – which is why I still didn’t hesitate to buy one three years after it was introduced, when it became obvious it was time to retire my K2500XS.

Still, it’s worth noting that there have been some compromises along the way. Most notably, there is no on-board support for recording samples. Samples can be loaded from USB, arranged into keymaps, looped, and used extensively, but the assumption is that they’ll be recorded elsewhere. This makes a great deal of sense to me but it may be an issue for some.

Also lost along the way were digital outputs, integrated ribbon controllers, and a dedicate breath controller input from earlier Kurzweil keyboards. Aftermarket MIDI alternatives exist, but of course they’re never as convenient as something built-in.

One of the more peculiar aspects for a new adopter is the lack of any dedicated buttons for editing programs and sequencing. Instead, soft keys are used to initiate editing or song recording modes and the ten “favorites” buttons are repurposed. It turns out there’s a reason for this…

From Stage Piano to Workstation

The Forte hardware represents a significant departure from prior Kurzweil architectures, and the new screen required redesigning the user interface for every feature. Rather than delay its introduction for years while adapting every feature, the R&D team opted to focus on a core set of features to launch with.

This is why the Forte is widely perceived as a Stage Piano rather than a full-fledged synthesizer or workstation, because that’s how it was introduced and those were the features available on day one.

The transformation that has taken place since is nothing short of remarkable. Firmware upgrades have added full VAST editing, string resonance, support for loading user samples in flash storage, a full multi-track sequencer, arpeggiation, and the triggered riffs features. Over the course of several years the Forte has become a full-fledged workstation again with the latest batch of features showing up in early 2018 shortly after NAMM.

Room for Improvement

While I’m delighted by all of the improvements over the years, there are certainly areas where Kurzweil feels like they’re behind the curve. There are no free-running oscillators, for example. There’s also nothing approaching audio-rate modulation. In fact the Forte shares the same modulation clock as the original K2000: every controller, LFO, and envelope is sampled 50 times a second. The fact that this hasn’t changed over the years is a shame, though of course not every program calls for anything more. There are still plenty of times when it would come in handy.

Usability is also an area ripe for reinvention. It’s hard work to make something as flexible as this instrument easy to use, but it would be time well spent. Too many find the depth intimidating and never get past using basic presets.

Still Complex, Still Worth It

Kurzweil’s instruments have a reputation for being complex, and there’s no doubt that’s well-earned. There’s a lot of menu diving involved if you want to make the most of the instrument, but then there’s a lot to be gained by doing so. It’s simply one of the most sophisticated digital synthesizers available as an integrated hardware instrument.

It also happens to make a phenomenal controller, with full access to sixteen layers that can be split, stacked, and have the complete range of performance controls assigned to them in sophisticated “Multi” configurations. Each layer can refer to internal programs, classic MIDI connections, or USB MIDI output with a dizzying array of options.

It’s easy enough to pick up and play, but if you start to look under the surface you’re likely to find enough depth to intrigue or terrify you, depending on your personal inclination.